Measure Percolation.

Determine the capability at which your soil absorbs liquid.

How to Run a Percolation Test Part 1

The following steps outline the procedure for performing a Percolation Test. This is part 1 in our series on How to Run a Percolation Test.

  1. Dig at least six test holes. The holes should be:
    • Evenly spaced, approximately 30-40 feet apart, but not less than 30 feet, in the area of the proposed septic field.
    • At least six inches in diameter. Larger holes are acceptable, but will require more water.
    • Dig to a depth of 24 inches.
    • No closer than 3 feet to the 48-inch test hole.
    • No closer than 75 feet to the nearest water well or proposed water well.
    • No closer than 5 feet to any lot line or easement.
    • No closer than 20 feet to any building.
    • Not located in any easement or flood plain area.
    • Not located in any area that has previously failed a percolation test.
  2. Dig a 48-inch test hole in the lowest part of the test area.
  3. The bottom and sides of each 2-foot test hole may be roughened with a saw blade, knife, or other sharp instrument. It is advisable to roughen those surfaces, which may become smeared with mud during the digging process. Smearing of those surfaces will tend to reduce the seepage rate. Remove all loose soil from the bottom of the holes.
  4. Fill each of the 2-foot test holes with water and refill as necessary to maintain a minimum depth of 12 inches for a period of at least four hours. This is the presoak. It must be conducted between 12 noon and 4 o'clock p.m. the day before the test. Health Department technicians may spot check the presoak to make sure it is being done properly. Note: DO NOT put any water in the 48-inch test hole.